Adjustable pattern shoe for lens edging machine



March 3, 1970 M. o. BRANDT ADJUSTABLE PATTERN SHOE FOR LENS EDGING MACHINE Filed March 19 1968 .T n ma NB 0. 0 M M 0 0 5 6 6 i J 4 6 I 4 w w fi Q k M\ 1 M6 6 l2 2 5 6 United States Patent 3,498,005 ADJUSTABLE PATTERN SHOE FOR LENS EDGING MACHINE Milo O. Brandt, Stun-bridge, Mass., assignor to American Optical Corporation, Southbridge, Mass, a corporation of Delaware Filed Mar. 19, 1968, Ser. No. 714,177 Int. Cl. B24b 9/14 U.S. Cl. 51101 6 Claims ABSTRACT OF THE DISCLOSURE A pattern shoe for a lens edging machine having a base and an upper surface covering of thin fiat spring stock shaped to conform intimately to the configuration of the base when relaxed thereagainst. A cam is incorporated in the base by means of which the surface covering may be selectively deflected upwardly away from the base to increase the effective height of the shoe in the edging machine. The cam may be operated to release the surface covering whereby, under the influence of its spring tension, it will automatically assume the aforesaid relaxed conformity with the base to lower the effective height of the shoe.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to lens edging machines in general and more particularly to improvements in edging machine pattern shoes.

Description of the prior art In the lens edge grinding art, it is currently a common practice to employ two stage grinding operations wherein the lenses are rough ground to an oversized condition of the final contour shape desired and then finished by fine grinding to precisely the desired finished size and contour shape.

The aforesaid two stage grinding operations are presently being performed with the necessity of constant alertness on the part of the machine operator in remembering to adjust his machine for oversize lens grinding prior to commencing a lens edging operation and taking care in resetting the machine for control of finish size in the second or last stage of the grinding operation for each lens so processed. Thus, with the requirement for making four lens size adjustments of the machine per each pair of matched ophthalmic lenses produced for subsequent mounting in respective spectacle frames, operator fatigue becomes a serious problem in the course of a work day. Fatigue, accordingly, is attended by the not uncommon result of a costly scrap yield attributable to inadvertence in making the repetitious machine adjustments, each of which require close scrutiny of size indicating scales.

Perhaps equally as serious a problem is that of operator fatigue imposing a high incidence of error in making identical finish size settings for each lens of a pair thereof to be mounted for ophthalmic use and the consequence of poor fitting of one or both lenses in their intended supporting means, e.g. spectacle frame.

An object of the present invention is to overcome these and other related problems in two stage lens edging operations by making it possible for a lens edging machine to be operated with one setting (i.e. the finished size setting) during the entire course of edge finishing both lenses of an intended matched pair thereof and/or the production of any successive number of such pairs or individual lenses intended to have the same finished size.

SUMMARY OF THE INVENTION In achieving the aforesaid result of successively producing the lenses of a matched pair or any number thereof with a single size setting adjustment of a lens edging machine the present inventive concept, briefly described, is as follows:

With a minimum of alteration of current lens edging machine design, the present invention incorporates in the lens size setting mechanism of the machine, an adjustable lens pattern shoe.

The shoe is of substantially the usual form in having a base portion of the proper curved shape for finishing lenses in the machine. Novel features of the shoe, however, include an upper surface covering of thin flat spring stock shaped to conform intimately to the configuration of the base when relaxed thereagainst. Cam means incorporated in the base is operable to effect deflection of the surface covering upwardly away from the base a precontrolled amount for increasing the effective height of the shoe in the edging machine. The cam means is also operable to release the surface covering from the aforesaid raised condition whereby, under its spring tension, it will automatically assume the previously mentioned conformity with the base of the shoe thereby lowering the effective height of the shoe.

Thus, it can be seen that with the surface covering in its relaxed condition and the conventional size setting mechanism of a lens edging machine set at the finished size desired of a lens or number of lenses to be edge ground, the first stage of a lens edging operation, i.e. rough grinding to oversize, is accomplished by simple operation of the cam means causing upward deflection of the surface covering to increase in the effective height of the shoe.

For finish grinding of the same lens to its desired final size, operation of the cam means to release the surface covering and effect automatic lowering thereof accomplishes this end.

Thus, as it will become apparent hereinafter, raising and lowering of the effective height of a lens edging machine pattern shoe, according to principles of this invention, for respectively increasing and decreasing the resultant size of lenses being edged (i.e. rough grinding and finish grinding) is accomplished by a simple flick of the cam means without disturbing the setting of the lens size setting mechanism proper. With a single setting of the size setting mechanism lenses can be rough ground (oversized) and finish ground without the usual requirement for continually resetting the sizing mechanism and the attending chance of human error or error resulting from backlash or other mechanical faults of the mechanism. Fatigue of the operator is avoided by the present inventive concept of not having to read lens size scales between rough (oversize) grinding and finish grinding operations regardless of the number of lenses worked upon after a finish size setting for the lenses has once been established. It will become apparent hereinafter that operation of the pattern shoe cam means does not require visual alertness.

As a corollary of the structural arrangement of the presently contemplated pattern shoe, the cost of maintenance due to wear is minimized by simple low cost replacement of the surface covering as needed. The base and cam mechanism of the shoe are, at all times, protected from wear by the surface covering, the only component against which edging machine patterns are revolved.

DESCRIPTION OF THE DRAWING FIG. 1 illustrates, in perspective, one embodiment of the invention applied to exemplary lens edging apparatus;

FIG. 2 is an enlarged rear perspective view of the embodiment of the invention shown in FIG. 1 with a substantial portion of the aforesaid apparatus broken away; FIG. 3 is a fragmentary vertical cross-sectional view taken generally along line 33 of FIG. 2 looking in the DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is illustrated lens edging machine incorporating a preferred embodiment of the invention, namely pattern shoe 12, detailed in FIGS. 2-4.

Machine 10 is exemplary of a type of lens edging apparatus to which pattern shoe 12 is applicable. Details of the construction and operation of machine 10, particularly with regard to the operation and function of patterns and pattern shoes in general, are clearly set forth in US. Patent No. 3,119,206 assigned to assignee of the present application and, accordingly, will not be dealt with herein. Those interested in such details may refer to Patent No. 3,119,206.

The present invention relates more particularly to improvements in pattern shoe 12.

Lens size setting mechanism 14 (FIG. 1) is used to adjust shoe 12 to settings of height or level relative to the effective lens abrading portion 16 of grinding Wheel 18 according to the finished size desired of the work piece (lens L).

As explained in the aforementioned Patent No. 3,119,- 206, thearrangement of a calibrated dial 20 and index plate 22 are used to determine proper settings of the height of shoe 12 for desired finished sizes of lenses L being worked upon. That is, dial 20 is calibrated for direct readings of lens size and, heretofore, in a first step of edge grinding a lens L, i.e. oversize grinding, it was necessary to dial a size greater than the desired finished size with extreme care being taken to return the size setting mechanism back to a proper setting of finished size prior to proceeding with the final step of finishing the lens.

According to this invention, the same (i.e. one) dial setting of mechanism 14 is used for both the oversize rough edge grinding and finish grinding of a lens or succession of lenses intended to all have the same finished size, regardless of shape. The shape of lens L is determined by the selection of pattern 24 in a manner fully explained in the aforementioned US. Patent No. 3,119,206.

THE IMPROVEMENT In referring more particularly to FIGS. 2, 3 and 4, it will be seen that shoe 12 comprises base 26 suitably secured, e.g. with screws 28, to bracket 30 of mechanism 14.

Base 26 having curved upper surface 32 is provided with cover 34 formed of thin flat spring stock. Cover 34 is preshaped to conform intimately to the curvature of surface 32 when in a relaxed condition. One end 36 of cover 34 is fixed to base 26 with screws 38 and its opposite end 40 is restrained from lateral displacement on base 26 by one or more cap screws 42.

Screws 42 extend through slots 44 in cover 34 which allows that end of cover 34 to slide along the top of base 26 when cover 34 is deflected upwardly intermediately of its opposite ends. Lifting of end 40 away from base 26 is prevented by the heads of screws 42.

Cam 46 is seated in a semicircular channel or socket 48 in base 26 which extends transversely across the width of base 26 beneath cover 34 intermediately of opposite ends 36 and 40 of the cover. Cam 46 is essentially a rod having a section of its length between its opposite ends 50 and 52 (FIG. 2) recessed or cut-away to a depth of one-half its diameter, i.e. to a size matching that of semicircular socket 48. The semicircular section (FIGS. 3 and 4) of cam 46 extends across the full width of cover 34 as lift 54 for deflecting cover 34 upwardly when cam 46 is rotated in socket 48 to the position illustrated in FIG. 4. The circular ends 50 and 52 of cam 46 function in socket 48 as journals keeping the cam in axial coincidence with socket 48 at all times during rotation thereof.

Representative of means which may be provided for rotating cam 46 is knob 56 fixed to end 52 of the cam.

Fr m the foregoing, it should be apparent that raising and lowering of the effective height of shoe 12 per se (i.e. cover 34) in machine 10 is effected by rotating cam 46 with knob 56 to the positions shown in FIGS. 4 and 3 respectively.

In FIG. 4 it can be seen that the effective height of shoe 12 is increased to its maximum by deflection of cover 34 with lift 54 and in FIG. 3 the height of shoe 12 is lowered to its minimum by lift 54 being rotated into socket 48 wherein it is below surface 32 of base 26 and cover 34 is permitted to assume, under its spring tension, its relaxed conformity with surface 32.

Circular ends 50 and 52 of cam 46 adjacent the opposite edges of cover 32 prevent withdrawal of cam 46 from socket 48 when cam 48 is in all positions but that shown in FIG. 4. When in the FIG. 4 position, however, the spring tension of cover 34 forcing ends 50 and 52 of the cam into socket 48 frictionally hold cam 46 against accidental displacement.

In carrying out a two stage lens edging operation (rough edging to oversize and fine edging to finish size) with machine 10, dial 20 is set to the finish size desired of lens L and lift 54 of cam 46 is positioned as shown in FIG. 4. The usual edging operation is effected with the result of lens L being gound oversize by the amount X shown in FIG. 4, i.e. the distance cover 34 is raised above surface 32 of base 26.

With lens L in the same position on grinding wheel 18, or moved laterally to another position, and lift 54 of cam 46 rotated to the position shown in FIG. 3, another edging operation is eflected to grind lens L to its finished size. No change in the size setting of dial 20 is made during the aforesaid two stage edging operation nor is it required in successive edge grinding operations on any number of lenses intended to have the same finished size, regardless of changes that may be required in shape of the lenses. Lens shapes are changed by substituting appropriately shaped patterns of standard size for pattern 24 with no effect upon size control.

Cam 46 can be operated by tactile sensation with or without a glance at shoe 12 since, when turned to cause lift 54 to approach the position shown in FIG. 3, the spring tension of cover 34 snaps lift 54 into place. When turned to the position shown in FIG. 4, a feeling of the resistance of spring cover 34 to deflecting can be sensed as indicating maximum deflection thereof. Thus, no operator fatigue is experience in a days work of setting and resetting machine 10 for rough and finish lens edge grinding operations. Only when the finished size of lenses is required to be changed is it necessary to adjust dial 20. Thus, from one lens to the next in successive two stage lens edging operations, differences in finish size settings due heretofore to inadvertent inaccuracies of repeated dial setting is obviated.

It is also pointed out that it is immaterial to matters of important concern in this invention whether two section (coarse and fine) grinding wheels 18 are used with a shift being made from one section of the wheel to another before each stage of the edging operation or whether the entire two stage grinding operation is carried out in one position on the grinding wheel 18.

It will, however, be appreciated that with the embodiment of the invention shown in FIGS. 2-4 the amount X to which lenses L are ground oversize is fixed for all lenses worked upon, as determined by the diametral size of cam 46 and its corresponding socket 48.

FIGS. 5' and 6 illustrate a modification of the invention wherein means is provided for selectively adjusting the throw of the cam whereby the amounts X (FIG. 4) to which lenses may be ground oversize can be varied.

Cam 46' in FIGS. 5 and 6 is substantially identical to cam 46 of FIGS. 2-4 with respect to its having circular opposite ends 50', 52 and operating knob 56 fixed to end 52.

Intermediately of ends 50' and 52', however, cam 46' is recessed to a depth which, with plate 60 placed therein, will position the plane of the upper surface of plate 60 substantially diametrically across the circular ends 50' and 52. Plate 60, which in this case constitutes the lift 54 of cam 46, is releasably secured to cam 46' with cap screws 62 extended through slots 64. Thus, with screws 62 loosened, plate 60 may be adjusted laterally according to the amount of throw desired of lift 54 and clamped thereinplace by tightening the screws.

Cam 46 is utilized in base 26 of shoe 12 in the manner shown and described with relation to the embodiment of the invention depicted in FIGS. 2-4. In adapting cam 46' to base 26 a slight modification of socket 48 (not shown) is required to accommodate for the overhanging lift 54' of plate 60. This simply requires enlargement of the portion of socket 48 between its opposite ends by an amount suflicient to allow lift 54 to be rotated freely therein.

The illustrated size and shape of the opposite ends of socket 48 is preserved for journaling ends 50 and 52' of cam 46' therein.

1. An adjustable pattern shoe for lens edge grinding apparatus comprising:

a base having a cylindrically curved upper surface;

a cover of thin fiat spring stock extending from adjacent one end of said upper surface toward an opposite end thereof and shaped to substantially intimately conform to the curvature of said surface when relaxed thereagainst;

means for securing opposite ends of said cover to said base, said means permitting at least one of said ends to slide longitudinally along said surface; and

cam means in said base for selectively deflecting said cover upwardly away from said curved surface of said base intermediately of its length to increase the effective height of said shoe and for selectively releasing said cover from such deflection to decrease the effective height of said shoe.

2. An adjustable pattern shoe according to claim 1 wherein said cam means includes an elongated lift of uniform shape and size extending beneath said cover transversely across the full width thereof.

3. An adjustable pattern shoe according to claim 2 wherein said cam means further includes journaling comprising a circular journal adjacent each of opposite ends of said elongated lift, socket means in said base for receiving said journals and means for rotating said cam means in said journaling.

4 An adjustable pattern shoe according to claim 3 wherein said socket means is of semicircular cross-sec tional shape having a diametral dimension substantially equal to that of said journals and said elongated lift is of a cross-sectional shape corresponding substantially to the shape of said socket means.

5. An adjustable pattern shoe according to claim 3 wherein said lift is adjustable in directions normal to respective axes of said journals.

6. An adjustable pattern shoe according to claim 5 wherein said lift comprises a rectangular plate extending longitudinally between said journals of said cam means, said plate having an upper surface disposed substantially in the plane of corresponding diameters of said journals and means for releasably securing said plate in preselected dispositions of adjustment according to amounts of throw desired of said cam means for deflecting said cover in the operation of said cam means.

References Cited UNITED STATES PATENTS 2,686,993 8/1954 Mentley 51-232 X 2,821,050 1/1958 McCarthy. 3,332,172 7/1967 Stern.

OTHELL M. SIMPSON, Primary Examiner 

